Essential COM

, DLL . , DLL . , DLL , , DLL . , DLL, API- CoFreeUnusedLibraries:

 void CoFreeUnusedLibraries(void); 

. CoFreeUnusedLibraries DLL, , . DLL DllCanUnloadNow, .

DllCanUnloadNow, DLL , :

 HRESULT DllCanUnloadNow(void); 

DLL , S_OK. DLL , S_FALSE. DLL , . , DLL . , DLL (lock count) :

 LONG g_cLocks = 0; void LockModule(void) { InterlockedIncrement(&g_cLocks); }  void UnlockModule(void) { InterlockedDecrement(&g_cLocks); } 

DllCanUnloadNow :

 STDAPI DllCanUnloadNow(void)    { return g_cLocks == 0 ? S_OK : S_FALSE; } 

O LockModule UnlockModule.

, DLL : , IClassFactory::LockServer. , DllCanUnloadNow . , ( , ) AddRef:

 STDMETHODIMP_(ULONG) Chimp::AddRef(void)  {     if (m_cRef == 0) LockModule();     return InterlockedIncrement(&m_cRef); }  

Release:

 STDMETHODIMP_(ULONG) Chimp::Release (void) {     LONG res = InterlockedDecrement(&m_cRef);     if (res == 0) {         delete this;         UnlockModule();     }     return res; } 

, ( , ), , AddRef Release :

 STDMETHODIMP_(ULONG) ChimpClass::AddRef(void)  {     LockModule();     return 2; } STDMETHODIMP_(ULONG) ChimpClass::Release (void)  {     UnlockModule();     return 1; } 

, IClassFactory, IClassFactory::LockServer:

 STDMETHODIMP ChimpClass::LockServer(BOOL bLock) {     if (bLock) LockModule();     else       UnlockModule();     return S_OK; } 

6, IClassFactory::LockServer , .

, CoFreeUnusedLibraries/DllCanUnloadNow (race condition). , , DLL, CoFreeUnusedLibraries. , . , Windows NT 4.0 Service Pack 2 . Service Pack 2 , DLL , , DLL CoFreeUnusedLibraries, DLL DLL, . , DLL CoFreeUnusedLibraries, , Release ¹. , DLL , .

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¹ , Windows NT 5.0 , DLL . SDK.